Section 25. Time-Based Flow Management (TBFM)

1. GENERAL

Time-based flow management (TBFM) is a foundational decision support tool (DST) for time-based management in the en route and terminal environments. TBFM's core function is the ability to schedule aircraft within a stream of traffic to reach a defined constraint point (e.g., meter fix/meter arc) at specified times, creating a time-ordered sequence of traffic. The scheduled times allow for merging of traffic flows, while minimizing coordination, reducing the need for vectoring/holding, and efficiently utilizing airport and airspace capacity. The TBFM schedule is based on current aircraft estimated time of arrival at key defined constraint points based on wind forecasts, aircraft flight plan, the desired separation at the constraint point and other parameters. The schedule applies time-based spacing only when needed to maintain the desired interval at one or more constraint points.

1. PURPOSE

1. This section establishes the purpose of TBFM.
2. TBFM enables the use of time-based management in the en route and terminal environments to enable gate-to-gate improvements in operational efficiencies by:

1. Applying spacing only where needed.
2. Allowing for the routine use of PBN operations.
3. Capitalizing on advanced aircraft Flight Management System (FMS) capabilities.
4. Adding more predictability to the ATC system.

1. POLICY

When departure and or arrival flows are subject to TMIs, or when supporting PBN procedures, TBFM must be used to the maximum extent feasible in preference to miles-in-trail initiatives. Procedures for use of the capabilities within TBFM, in support of PBN operations and TMIs, must be documented in facility directives (e.g., LOAs, SOPs).

1. DEFINITIONS

1. Time-Based Flow Management (TBFM). A foundational decision support tool (DST) for time-based management in the En Route and Terminal environments. TBFM's core function is the ability to schedule aircraft within a stream of traffic to reach a defined constraint point (e.g., meter fix/meter arc) at specified times, creating a time-ordered sequence of traffic. The scheduled times allow for merging of traffic flows, while minimizing coordination, reducing the need for vectoring/holding, and efficiently utilizing airport and airspace capacity. The TBFM schedule is based on current aircraft estimated time of arrival at key defined constraint points based on wind forecasts, aircraft flight plan, the desired interval at the constraint point and other parameters. The schedule applies the right spacing to the right aircraft, at the right time. This includes, but is not limited to, SCM, ACM, EDC, IDAC, GIM-S, departure scheduling and extended/coupled metering.
2. Single Center Metering (SCM). Capability that provides personnel providing traffic management services with the ability to view and manage arrival flows to an ARTCC's internal airports.
3. Adjacent Center Metering (ACM). An extension of SCM that provides metering capability to neighboring facilities.
4. Constraint Satisfaction Point (CSP) . A meter arc, meter fix, meter point or other meter reference element.
5. Coupled Scheduling (CS)/Extended Metering (XM). Adds additional CSPs for an aircraft to meet the scheduled time of arrival along their route. This results in a more optimal distribution of delays over a greater distance from the airport or CSP.
6. Ground-Interval Management-Spacing (GIM-S). Capability that provides automated speed advisories prior to descent to enable en route controllers to meet the scheduled time of arrival (STA).
7. En Route Departure Capability (EDC). Scheduling capability that assists personnel providing traffic management services in formulating release times to a CSP to manage a miles-in-trail restriction.
8. Departure Scheduling. The action of personnel to obtain a runway departure time from TBFM for release of aircraft. Departure scheduling can be used to schedule into an arrival flow or into EDC.
9. Integrated Departure/Arrival Capability (IDAC). Capability allows the tower to conduct departure scheduling electronically.
10. Managing Facility. That facility which exercises control over TBFM settings and the relevant metering operation.
11. Supporting Facility. A facility that maintains an ancillary relationship to the managing facility in supporting TBFM-related functions.
12. Graphical User Interface (GUI). The computer interface that displays TBFM data utilizing timeline graphical user interface (TGUI) and planview graphical user interface (PGUI).

1. Full Controlling (FC). The ability to exercise control over TBFM settings and the relevant metering operation.
2. Limited Control (Partial Control GUI) (PC). The ability to manage specific TBFM settings and activities for relevant metering operations.
3. Non-Controlling (Non-Control GUI) (NC). A GUI that only has monitoring capability.
4. Terminal Control GUI (TC). A GUI specific to TSAS operations that resides in the TRACON.

1. Reschedule/Global Reschedule. The recalculation of generated frozen scheduled times of arrival (STA) resulting from an action taken at the TBFM GUI. Reschedule/global reschedule, also commonly referred to as “rescheduling” or “rippling,” can be executed as an independent function but is also accomplished when changes to TBFM configurations or settings occur.
2. Terminal Sequencing and Spacing (TSAS). Extends scheduling and metering capabilities into the terminal area and provides metering automation tools to terminal controllers and terminal traffic management personnel. Those controllers and traffic management personnel become active participants in time-based metering operations as they work to deliver aircraft accurately to CSPs within terminal airspace to include the runway in accordance with scheduled times at those points. Terminal controllers are better able to utilize efficient flight paths, such as standard instrument approach procedures (SIAPs) that require a navigational specification (NavSpec) of RNP APCH with Radius-to-Fix (RF) legs, or advanced RNP (A-RNP), through tools that support the merging of mixed-equipage traffic flows. For example, merging aircraft flying RNP APCH AR with RF, A-RNP, and non-RNP approach procedures). Additional fields in the flight plan will identify those flights capable of flying the RNP APCH with RF or A-RNP procedures, and those flights will be scheduled for those type procedures when available. TSAS will schedule these and the non-RNP aircraft to a common merge point. Terminal traffic management personnel have improved situation awareness using displays that allow for the monitoring of terminal metering operations, similar to the displays used today by center traffic management personnel to monitor en route metering operations. See also TSAS Notice when available.
3. Speed Advisory. Speed advisories that are generated within TBFM to assist controllers to meet the scheduled time of arrival (STA) at the meter fix/meter arc and terminal meter points.

1. RESPONSIBILITIES

1. The managing facility (ARTCC/TRACON) must:

1. Determine appropriate TBFM settings and parameters and enter them into the TBFM system and coordinate as necessary.
2. Determine TBFM activity timeframes and coordinate start/stop times with the ATCSCC and affected facilities.
3. Communicate TBFM activity start/stop information to operational areas, operating positions, and supporting facilities, and log.
4. Enable/disable sector meter list as coordinated.
5. Monitor internal and upstream compliance and take appropriate action.
6. Monitor TBFM airborne delays and initiate actions, as appropriate, when values exceed or are projected to exceed delays that can be absorbed by control sectors. Notify the OS or affected areas/sectors of actions taken and expected outcomes.
7. Notify ATCSCC when unable to use TBFM capabilities, provide supporting justification, and log.
8. Coordinate internally with affected areas and with supporting facilities before taking action when changes to the metering strategy or updates to the TBFM schedule are necessary.

1. Ensure TBFM coordination procedures are placed into local SOP or LOAs between facilities.

1. Use TBFM to determine release times for facility-controlled departures to a metered airport.
2. Ensure TBFM adaptations are maintained to reflect current operations.
3. Ensure trouble reports are submitted and reconciled.
4. Ensure TBFM training is completed.
5. Provide support to other local facilities with TBFM equipment.

1. The ATCSCC must:

1. Maximize NAS efficiency and ensure optimal distribution of any delay.
2. Maintain awareness of all TBFM related operations and/or activities.
3. Include the status of pertinent TBFM information on planning telecons and on the National Airspace System status display.
4. Prioritize daily TBFM actions based on NAS and/or facility constraints.
5. Establish and maintain multifacility communications when necessary for TBFM operations.
6. Log TBFM related activities.
7. Be the final decision authority to resolve TBFM conflicts.

1. Supporting facilities (ARTCC/TRACON/ Tower) must:

1. Determine appropriate local TBFM settings.
2. Ensure TBFM settings are entered via TBFM TGUI, kept current, and coordination is accomplished.
3. Determine TBFM activity timeframes and coordinate start/stop times with the ATCSCC and affected facilities.
4. Communicate TBFM activity start/stop information to operational areas, operating positions, and supporting facilities, and log.
5. Enable/Disable sector meter list as coordinated, where applicable.
6. Use TBFM to determine release times for facility controlled departures to a metered airport.
7. Monitor arrival and departure flows for potential metering actions/changes.
8. Notify managing facility when unable to use TBFM capabilities, provide supporting justification, and log.
9. Monitor internal and upstream compliance and take appropriate action.
10. Ensure TBFM training is completed.
11. Through the appropriate managing facility, supporting facilities must:

1. Ensure adaptations are maintained to reflect current operations.
2. Ensure trouble reports are submitted and reconciled.
3. Provide support to other local facilities with TBFM equipment.